Notwithstanding the increased interest in energy conversion over recent decades, no substantial advances have been made in increasing the conversion efficiency of electric motors. Rather, the art has made incremental advances relating to improved magnetic materials, more powerful permanent magnets, and sophisticated electronic switching devices. Such improvements, at best, relate to very small increases in overall efficiency, usually gained at very considerable expense.
Patents in this area include: U.S. Pat. Nos. 2,917,699; 3,132,269; 3,321,652; 3,956,649; 3,571,639; 3,398,386; 3,760,205; 4,639,626 and 4,659,953. Also in this area are EPO patent no. 0174290 (March 1986); German patent no. 1538242 (October 1969); French patent no. 2386181 (October 1978) and UK patent no. 1263176 (211972).
The basic concept employed in earlier motor art is the interaction between a current carrying conductor(s) and a magnetic field of some kind. This fact is true regardless of motor type. This basic concept appears in DC motors, single phase AC motors, poly phase induction slip motors, which utilize a rotating magnetic field, and in poly phase synchronous motors with externally excited electromagnetic cores, or permanent magnet cores as the case may be.
Other types of designs may be found, for example, in the design of stepper motors, which utilize a magnetic “ratcheting” action upon magnetic material in the armature, in response to applied pulses of current, and various types of reluctance motors in which the rotor moves with respect to a salient pole piece experiencing a large variation in air gap during its motion. But, these devices typically do not have a constant and continuous air gap of fixed dimension between the rotor and the stator.
The prior art has not produced a multiple phase, multiply segmented stator with individual, obliquely disposed, laminated armatures devoted to each stator section, such that each stator/rotor combination employs a continuous air gap of constant dimension, regardless of the elliptical profile of said armatures, but not employing any current carrying conductors, coils, windings or bars within or upon the armatures, as a means of producing torque upon the output shaft.
Nor can it be said that the prior art has arranged such motors to cooperate in “parallel fashion,” through a reduction gear arrangement so as to provide an amplification of torque while sharing the mechanical load.
A previous example exists which describes an alternator having a single rotor canted at an angle, and makes use of the unique rotor design featured within this disclosure. Said rotor was introduced in the power conversion device entitled “Alternator Having Improved Efficiency,” which was invented by James F. Murray III, filed as application Ser. No. 07/112,025, on Oct. 21, 1987, and later granted U.S. Pat. No. 4,780,632 on Oct. 25, 1988, and is herein incorporated by reference.
There are marked differences between the presently disclosed inventions and the inventions disclosed in the “Alternator Having Improved Efficiency,” patent (“the Alternator Patent”). A few non-limiting examples of which are listed as follows:
1.) Alternator of the Alternator Patent can be operated as a motor only when used in conjunction with the basic motor concepts described herein (i.e., requires field flux and current-carrying conductors).
2.) Alternator of the Alternator Patent does not require salient pole projections in order to operate.
3.) Alternator of the Alternator Patent makes use of an electromagnetic field winding, or a permanent magnet as its source of magnetic flux.
4.) Alternator of the Alternator Patent does not require a shaft position indicator, or a commutator, of any kind in order to function.
5.) Alternator of the Alternator Patent does not require a position sensitive, electronically controlled, pulsed power supply, in order to generate electricity.
Other similarities between the Alternator Patent and the presently disclosed inventions include elements possessed by most rotating power converters, such as bearings, shafts, end bells, laminations, mechanical housing, etc.
As evident from the above discussion, electric motors have been in use for well over 100 years, and they exist in several forms. While, the basic concept has not substantially changed, the manner in which the switching of supply current is controlled has evolved. However, existing motors typically experience performance limitations due to the manner in which Back EMF and inductive field energy are treated. The generation of Back EMF in motors of all kinds is chiefly due to two things: the movement of conductors through a magnetic field, called Speed Voltage, and the rate of change of current through a winding, called Transformer Voltage. Conventional wisdom suggests that Speed Voltage Back EMF is totally unavoidable, and in fact, is necessary for the transformation of electrical power into mechanical power in a typical motor. However, one drawback of Speed Related Back EMF is its parasitic nature that serves to degrade the potential supplied to the motor from an outside source (i.e., the source voltage).
The parasitic nature of Back EMF arises from, among other things, the mistaken assumption that Back EMF is required to produce torque. This, in turn, leads to design compromises which must be made in order to implement traditional electrodynamic machine geometries. Consider, for example, a conventional DC Motor consisting of a stator with salient field poles, and a rotor-armature with a self-contained commutator. Application of a DC current to the rotor leads produces a rotary motion of the rotor (i.e., motor action). However, the rotation of the rotor conductors in a magnetic field also induces a voltage in the conductor that opposes the current applied to the rotor leads (i.e., generator action). These facts actually demonstrate an important aspect of conventional machines; if standard design parameters are always followed, then any motor must perform as a generator while it is running, and any generator must perform as a motor while it is in operation. The explanation of this similarity is because both machines are dependent upon the same basic geometry for their functionality, and so, both motor and generator action occur simultaneously in both devices.
The above-described basic geometry of a conventional Speed Voltage based system results in the production of parasitic Back EMF as follows. In a Speed Voltage based system, the magnetic flux must interact with an electrical current-carrying conductor (e.g., rotor windings), thereby producing a mechanical force that generates a torque to turn the motor shaft (i.e., a motor action). The subsequent motion of the conductors through the magnetic flux produces a relatively high Back EMF (i.e., acts in opposition to the torque producing current) due to the motion of the conductors with respect to the magnetic flux (i.e., a generator action). In order to continue normal operation, and establish electrical equilibrium, any motor that produces a Back EMF having a constant average value, must draw down on the line-potential in order to overcome the effects of this parasitic Back EMF voltage. Thus, this process of source potential degradation due to Back EMF requires the input of considerable potential energy from the source in the form of a voltage in order to maintain normal operation.
Another design factor of conventional Speed Voltage dependent machines is that, typically, as the rotor turns from pole to pole the air gap between the rotor and the stator will vary in width (from a smaller gap when the rotor is “facing” a stator pole, to a larger gap when the rotor is “between” stator poles). This change in the air gap results in a change in the magnetic potential energy within the air gap resulting in the Back EMF component described above. These and other significant issues and inefficiencies persist in traditional DC motor designs.
Generally, three phase synchronous motors, (e.g., AC powered machines) are known in the art. Typically, this kind of motor relies upon a rotating magnetic field as its source of propulsion, but, unlike a standard three phase induction motor, a three phase synchronous motor typically employs a magnetic field core which is excited by an external source of DC current. The interaction of the DC field with the rotating AC field provides the mechanism for synchronizing the rotation of the rotor of the three phase synchronous motor with the rotation of the magnetic field created with current from a power plant generator, potentially located many miles away from the motor. Synchronization occurs when the DC field of the motor's rotor “locks into phase” with the rotating field produced by the AC-powered windings in the motor's stator.
Once this condition of phase lock is achieved, synchronous motors are generally capable of providing large output shaft torques at relatively high levels of operational efficiency, and they can also provide adjustable power factor control, which is desirable in certain industrial applications.
Some potentially undesirable aspects of existing synchronous reluctance motors are that they are typically not self-starting, and, consequently, they may require a starter motor, or some other initiating device. Existing synchronous motors also typically require an external source of DC power to excite the motor's internal rotor field. Other drawbacks also exist with current synchronous reluctance motor designs.
Currently, there are various types of reluctance motors including: synchronous reluctance motors, variable reluctance motors, and switched reluctance motors. Regardless of type, reluctance motors typically are most desirable in applications where a high power density at relatively low cost is desirable.
Existing reluctance motors are typically designed with multiple, salient electromagnetic poles situated upon a stator, and a rotor consisting of a soft magnetic material, such as laminated silicon steel which also has multiple pole projections emanating like spokes from the center of the rotor core. Typically, the number of rotor poles is typically less than the number of stator poles to ensure a maximum change in the magnetic reluctance as the rotor advances from one stator magnetic pole to another, thereby producing a large torque. This unequal rotor and stator pole arrangement also prevents multiple poles from aligning simultaneously which, if not prevented, could stall the motor.
Typically, existing reluctance motors carry no electric current conductors upon or within their rotors. Accordingly, when operated at synchronous speed, these motors produce no current-related losses within the rotor, in contrast with the losses found in typical induction slip motors. However, standard reluctance motors will produce a certain amount of torque-flutter, especially at lower rotational speeds, and the flux switching from pole to pole produces large changes in air-gap dimensions, which does produce a high degree of Back EMF. Other drawbacks also exist in current reluctance motor designs.
For example, existing designs for three phase synchronous reluctance motors employ stators that are typically configured to accept either wave windings or lap windings, thus producing a so-called current sheet which spins at synchronous speed, and produces a resultant magnetic field vector which does the same. This rotating magnetic field interacts with the DC-based field of the motor's rotor, and keeps it turning at 3600 RPM. However, there are some drawbacks to this arrangement. One drawback is that the distribution of copper windings in wave fashion around the inner periphery of the stator encourages a great deal of magnetic “coupling” between the various windings, such that the resulting current impedance becomes a “distributed characteristic” known as the synchronous impedance, the effects of which are unchangeable in the standard reluctance motor design. Another drawback of typical designs is that they also produce a Back EMF with a considerable degree of DC content, which is difficult to dissipate. Other drawbacks also exist.
Before turning to the improvements and advantages of the disclosed inventions, a brief review of some fundamental concepts for electric motor operation is instructive. The basic premise is that the force developed by a current carrying conductor immersed in a magnetic field is described as (equation 1):F=BlI, 
where, F is the force developed, B is the flux density, l is the conductor length, and I is the current. This simple equation suggests that a current-carrying conductor situated in a magnetic field will experience a force that is directly proportional to the applied current, the flux density and the length of the conductor. This principle underlies the operation of the millions of electric motors spinning every day in locations all over the world.
The voltage produced by a conductor moving through a magnetic field can be described using (equation 2):V=Blv, 
where, V is the voltage developed, B is the flux density, l is the conductor length, and v is the tangential velocity of the conductor as it rotates. Accordingly, if a conductor is moved through a magnetic field by an external motive force (e.g., a prime mover), then the voltage produced may give rise to a current in the conductor, and such a device exhibits generator action. Conversely, if a conductor is carrying a current, and thereby moves through a magnetic field under the influence of the current itself, the device exhibits motor action. However, in the act of moving through the field a voltage is produced within the conductor in accordance with equation 2, and acts in such a manner as to diminish the applied current responsible for the conductor's motion, and this produced voltage is typically referred to as a Back EMF.
Examining the actual power present in the system can be accomplished as follows. Mechanical power can be expressed as the product of Force and Velocity. Velocity is therefore missing from the first relationship (equation 1), but it can be included by multiplying both sides of equation 1 by the additional parameter:Fv=BlIv. 
The resulting expression now denotes a form of mechanical power expressed as (equation 3),Pm=BlIv, 
where, Pm denotes mechanical power.
In similar fashion, the voltage expression (equation 2) denotes only potential, not power. Electrical power can be expressed as the product of voltage and current. Current is missing from the second relationship (equation 2), but it can also be included by multiplication to both sides of the equation:VI=BlvI. 
The resulting expression now denotes a form of electrical power as (equation 4),Pe=BlvI. 
Note that BlIv (equation 3) is equal to BlvI (equation 4), and therefore, Pe must be equal to Pm. This analysis is as expected, and holds with current theories that stipulate the applied power is equal to the output power minus the system losses.
Another important factor to consider is the magnetic flux in a DC motor. The flux, Φ, can be expressed as (equation 5):Φ=LI, 
where L is the inductance and I is the current. Taking the derivative of the flux expression with respect to time, t, yields:dΦ/dt=d(LI)/dt. 
Substituting V for dΦ/dt gives (equation 6):V=LdI/dt+IdL/dt. 
The first term in equation 6 is the product of inductance (L) and the rate of change of current (I) with respect to time (t). This is the previously discussed Transformer Voltage Vt. The second term is the product of the current (I) and the rate of change of Inductance (L) with respect to time (t). This is the previously discussed Speed Voltage Vs. Thus the relationships for each Voltage type is:
Transformer Voltage (equation 7), Vt=L dI/dt, and
Speed Voltage (equation 8), Vs=I dL/dt.
Expressing Vt and Vs in terms of the energy can be accomplished as follows. The field energy, Pt, due to the Transformer Voltage may be expressed as follows:Pt=IVt. 
Substituting for Pt and Vt gives:
dE/dt=I dΦ/dt. Simplifying to (equation 9):dE=IdΦ. 
Equation 9 expresses the quantity commonly referred to as the reactive energy. The dissipative energy for the system can, likewise, be expressed as follows. Starting from equation 8, Vs=I dL/dt, and realizing that L=Φ/I, then L=Φ(I−1), and dL/dt=ΦI−2dI/dt.
Substituting (Φ I−2)dI/dt for dL/dt=gives:
Vs=I (−Φ/I2) dI/dt. Multiplying both sides of the equation by I yields an expression for dissipative power, Ps. But, VsI=dE/dt, therefore, Ps=dE/dt=−Φ dI/dt, and (equation 10):dE=ΦdI. 
Combining equation 9 and equation 10 the total energy in an air-gap is (equation 11):ET=IdΦ+ΦdI. 
The energy relationship described in equation 11 can be further explained with reference to FIG. 1, which depicts a plot of flux (Φ) versus current (I) of the air gap energy components. As shown, the line 100 represents the total magnetic energy given by (equation 12):Em=IΦ. 
The region 110 above line 100 indicates the (I dΦ) reactive energy region and region 120 below line 100 indicates the (Φ dI) dissipative energy region.
The relevance of this energy relationship can be further explained with reference to FIGS. 2A and 2B which show a cross-sectional representation of a prior art reluctance motor. As shown in FIG. 2A, rotor 210 is in a position between two stator 200 poles yielding the motors largest air gap 220 designated as (g1). In normal operation, when the magnetic poles are energized with the proper magnetic polarity, the flux lines thus created will reach across this gap 220 as they are formed, and cause the rotor 210 to rotate to the position depicted in FIG. 2B, thereby reducing the reluctance in the magnetic circuit and reducing the air gap 230 to its smallest dimension designated as (g2). A torque impulse is also created during this motoring action, and the average mechanical work which is delivered on the rotor 210 will be found to be directly equal to the change in energy (Φ dI) within the air gap.
Referring now to FIG. 3, which is a double graph representing the energy relationship for the prior art motor illustrated in FIGS. 2A and 2B. The plot labeled 300 corresponding to air gap (g1) represents the relationship between the excitation flux and the excitation current at the point in time where the gap dimension is largest (e.g., air gap 220 as depicted in FIG. 2A). Note the larger value of the excitation current (I1), and the relatively lower value of the associated flux (Φ1). This is due to the fact that the large air gap has a high value of magnetic reluctance, and therefore requires substantially more current to produce the associated value of flux (Φ1). This condition changes for the plot labeled 310 (corresponding to air gap g2), because the air gap has been greatly reduced, and much less current (I2) is required to establish and hold the flux (Φ2) within the magnetic circuit. Note that the current has reduced to value I2, and the flux has actually increased to value Φ2. This may sound like a positive result, but actually, it is not, because this large change in the flux (Φ) is also responsible for the production of an associated Back EMF.
For illustrative purposes, the following four calculations using equation 11 can be made representing the component energies associated with each air gap size (g1 and g2).
For a gap size g1: Φ1dI=(13.5)(18−12)=81 Joules, and I1dΦ=(18)(15−13.5)=27 Joules. For a gap size g2: Φ2dI=(15)(18−12)=90 Joules, and I2dΦ=(12)(15−13.5)=18 Joules.
Thus, each energy component has a different value, but much more interesting to note is that the total energies E1 and E2 which represent the energy for air gap sizes of g1 and g2, respectively, are equal (27+81)=(18+90)=108 Joules. This is consistent with the understanding that the motor shaft energy and motor input energy are equal in a motor of standard design, and co-exist within the motor structure. Hence, the term co-energy.
In further illustration of conventional DC motor operation, consider the following example of normal, Speed Voltage dependent operation. One skilled in the art will recognize that a number of the principles of DC motor operation illustrated in the following paragraphs are also applicable to AC motors. As depicted schematically in FIG. 4A, an exemplary standard DC motor with a power rating of 3.528 Horse Power has the following characteristics:
Full Load Speed=1800 RPM.
Continuous Shaft Torque=123.529 in-Lbs.
Terminal Voltage=124 Volts DC.
Full Load Current=26.326 amps.
Copper Losses=315.912 watts.
Other Losses=315.912 watts in the aggregate.
Back EMF Power Loss=2632.600 watts.
Shaft Power=3.528 H.P.
Total Input Power=3264.424 watts.
System Efficiency=80.645%.
Accordingly, if the proper voltage is applied to the motor terminals, and the mechanical load does not vary, the above properties should prevail indefinitely after thermal equilibrium has been reached. However, this same example DC motor will have drastically different properties upon first being started. This is illustrated by the diagram in the second diagram in FIG. 4B, showing the start-up, or in-rush operation.
At the instant illustrated, the DC motor has not yet begun to rotate, and there is no Back EMF, but the starting torque is relatively large at 637.986 in-lbs, which is 5.165 times the running torque. The Back EMF that develops as a function of the motor's increasing rotational speed reduces the start-up current of 135.965 amps down to the full load ampere (FLA) value of 26.326 amps. This “high start-up current,” behavior is standard and expected in conventional Speed Voltage dependent motors.
Bearing these facts in mind, it stands to reason that for two, otherwise-identical, electric motors, the one that employs a larger, or surplus, number of winding turns per pole would experience a comparatively higher inductance L, and correspondingly, a relatively higher total Back EMF, resulting from the sum of Vs and Vt. Accordingly, to avoid this occurrence, it is typical in the prior art of electric motor design that the winding turns per pole are generally kept to a minimum, for a given operational voltage, thus allowing the Speed Voltage component to drive the design criteria, and minimize the Transformer Voltage component.
However, this engineering trade-off, of keeping inductance L low by using fewer windings, diminishes the amount of stored energy in the motor's magnetic circuit, and causes motor performance to be tied to the characteristics imposed by the Speed Voltage component of the Back EMF, most notably, the requirement for a higher magnitude source voltage and reduced torque output. Other motor design drawbacks and Back EMF issues also exist in prior systems.